1. Field of the Invention (Technical Field)
The present invention relates to methods and apparatuses for remotely stopping vehicle engines, preferably by using microwaves with frequency and modulation characteristics that are matched to susceptibilities of specific vehicle engine control systems (ECS).
2. Background Art
Note that the following discussion refers to a number of publications and references. Discussion of such publications herein is given for more complete background of the scientific principles and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
Modern vehicle engines typically rely on computer control for such things as timing and air-fuel mixture. This control requires sensory input, and if interference can be added to the normal signals from these sensors, inaccurate feedback is provided to the ECS. If the difference between the actual signal and the “normal” signal is large enough, the ECS might simply ignore it, analogous to running in open loop mode. On the other hand, if the false signal is processed by the ECS and results in issuance of commands to change timing advance, air-fuel mixture, etc., the engine will potentially run poorly or stop.
Radiated microwave energy has been shown to stop modern internal combustion engines by disrupting the normal functions of the engine control unit (ECU) computer that controls the timing of the ignition and/or fuel delivery systems. Microwaves can couple into engine compartments via diffusion through the hood, slots, or from large gaps on the bottom. Of these coupling mechanisms, the first is insignificant because the attenuation of microwaves as they pass through the hood renders the signal on the other side extremely small. The other two mechanisms are rather frequency selective, depending heavily on the physical structure of the car. The distribution of microwave energy inside the engine compartment is likewise strongly dependent on frequency due to the physical layout of the various components. Because of this variance in the physical location, orientation, and interconnection of components within the ECS, in addition to the differing types of affected sensors, a particular narrow-band microwave signal which stops one vehicle is unlikely to stop another. Exceptions exist for obvious cases where the make and model of one vehicle bear much similarity to another due to manufacturer relationships (e.g. Plymouth Voyager and Dodge Caravan).
One significant drawback of microwave-based engine-stopping devices is the large size required, typically compared to available storage in a typical car, particularly a police squad car. These devices utilize high power and/or high bandwidth, so the required microwave source is large. Furthermore, the requirement for some directivity and relatively low microwave frequencies necessitates the use of large antennas. Also, the high power can permanently damage an ECU, and may result in collateral damage to other vehicles and people, such as bystanders using personal pacemakers.